The present invention relates to a coupler for light carried by an optical fiber. In particular it is desirable to be able to provide a single coupler for bi-directional operation of an optical fiber such that radiation transmitted along the fiber from a remote location can be detected to provide electrical signals corresponding to the modulation on the light. At the same time light, modulated in accordance with desired electrical signals, is to be applied to the optical fiber for transmission to the remote location. Such a function is important to bi-directional communications utilizing optical fibers.
In providing such a coupling function, it is desirable that the coupling to and from the optical fiber be accomplished in a single device. It is also important that the attenuation in the radiation supplied to and received from the fiber be as minimal as possible. Finally, it is important that cross talk, or reception by the detector of a portion of the radiation intended for transmission along the fiber to the remote location, be kept acceptably low so as not to impair the signal quality of the detected incoming light.
Such couplers are likely to be utilized in great numbers making it important for economical, high volume production to be available for such a coupler. At the same time such couplers are likely to be installed in the field where complex alignment procedures are impractical.